The invention relates to a tomographic apparatus for the production of transverse layer images of a radiography subject, comprising a patient support, comprising a radiation measuring arrangement which includes a radiation source which generates a beam of rays, fan-shaped in the layer plane, penetrating the radiography subject, the cross-sectional extent of said beam of rays perpendicular to the layer plane being equal to the layer thickness, and a radiation receiver which includes a series of detectors disposed transversely relative to the longitudinal direction of the support, and which determines the radiation intensity behind the subject, comprising a rotating device for the measuring arrangement for rotation about an axis extending parallel to the longitudinal axis of the patient support, comprising a measured value converter for the transformation of signals supplied by the radiation receiver into a tomographic image, and further comprising means for scanning a succession of transverse body segments and for calculation and reproduction of an x-ray shadow image whose length corresponds to the distance between the first and last of the transverse body segment scanned and whose width corresponds to the width of the radiation receiver.
A tomographic apparatus of this type is described in the German OS No. 2613809. In the case of this known tomographic apparatus it is possible to prepare two types of photographs; namely, through rotation of the x-ray beam in a plane and generation of output signals of the radiation receiver at different projections, a transverse layer image, a so-called computer tomogram, on the one hand; and, through a relative movement between the measuring arrangement and patient support with the measuring arrangement locked against rotation, an image similar to a conventional x-ray photograph, namely an x-ray shadow image, on the other hand. For the production of an x-ray shadow image, a mechanical movement, either of the patient support or the entire measuring arrangement, is necessary, since the radiation receiver always detects only one line of this x-ray shadow image for a given longitudinal position.